Continued participation in the cooperative studies of various therapeutic regimens in acute and chronic leukemia, multiple myeloma, lymphoma, childhood solid tumors and other hematologic and non-hematologic neoplasms to be studied by the Acute Leukemia Group B. Ancillary studies noted below will be investigated: 1. Serologic screening of multiple myeloma and lymphoma patients; 2. immunological profile of patients with hematologic neoplasias; 3. effect of immunotherapy on prolonging remission duration of acute and chronic leukemia; 4. immunological responses of leukemic patients to leukemic cell antigens.